As a method for optically connecting a plurality of optical devices, it has been known a process comprising the steps of disposing a substance which changes in refractive index when irradiated with a certain range of wavelengths of light (hereinafter referred to as “optical refractive index material”) in part or the whole of the space between optical devices and irradiating the optical refractive index material with light of wavelength causing the material to change its refractive index from at least one of the optical devices, or disposing a photosensitive material in part or the whole of the space between optical devices and irradiating the photosensitive material with light of wavelength causing the material to change its refractive index and insolubilizing the material from at least one of the optical devices, thereby to induce self-focusing to form a waveguide or an optical coupling between the optical devices (see, for example, Patent Document 1).
Patent Document 1: JP 8-320422 A
In order for the optical refractive index material to self-form an optical guide or an optical coupling in the process disclosed in Patent Document 1, the optical refractive index material must increase its refractive index in the irradiated part over the non-irradiated part. To achieve this, it is required that the kinds and the compounding ratio of components used to make the optical refractive index material, such as a high- or low-refractive monomer, a sensitizer, a polymerization initiator, etc., be selected strictly. Such selection of the formulation is very troublesome.
In case where the photosensitive material is used for self-formation of an optical guide or an optical coupling, insolubilization of part of the photosensitive material should be followed by developing processing. Therefore, the process involves technical restrictions and an increased number of steps for development. Thus, also in this case, the process needs very troublesome task.